This invention relates generally to the manufacturing of printed circuit board assemblies (PCBAs) and electronic components, and more particularly to a component tape feeder having splicing capabilities and a cover tape drive for reliably conveying a cover tape removed from an upper surface thereof.
The present invention is a spliceable tape feeder device for not only conveying components to a pickup location for attachment to a substrate using a pick and place machine, but also for reliably controlling the cover tape peeled therefrom to direct it toward a downward disposal location. Carrier tape used in tape feeding equipment typically comprises a plastic, paper or similar strip having depressions at regular intervals containing the part to be mounted on the substrate and a second, plastic cover tape covering the depressions to retain the components in the depressions during transport and use. Such tapes are generally of a limited length that is determined by the size of the components and the capacity of the supply reel that contains the components. However, this invention relates to a tape feeder device that can feed such carrier tapes in a variety of formats, wherein the feeder incorporates certain functions and features that enable splicing of the carrier tape from one reel to another, where the need to remove the feeder from the pick-and-place system is eliminated.
The preferred method for the automated construction of circuit boards requires the use of high speed pick and place machines that pick components from a feeder having a pickup location and place them at required locations on a printed circuit board for attachment. Pick and place machines rely on feeding mechanisms or feeders to reliably feed the required components to the expected pickup location. It is well-known in the industry to package small electronic components such as integrated circuit chips in a carrier tape that is characterized by a flexible strip with depressions formed at regular intervals along its length. A part is disposed in each depression and secured by a cover tape that is adhered along its edges to the carrier tape. Components that are packaged in a carrier tape require the cover tape be peeled away from the carrier tape and that the carrier tape be advanced to bring the next part to the pickup location. Normally, the cover tape is peeled back from the carrier tape at a point just prior to the pick location as the tape is advanced. In systems that are intended to enable spliceable feeding, the handling of the cover tape, after being peeled back from the carrier tape, is an important consideration. More specifically, it is important that such a feeder provides means for continual disposal of cover tape from an unlimited number of carrier tape feed reels.
Electronic components are packaged in carrier tapes in a variety of formats, depending on the size of the part being delivered. In particular, carrier tapes are available in varying widths and pitches. The width is the distance from edge to edge perpendicular to the length of the tape. Widths common in the industry are 8 millimeters to 56 millimeters and larger. The pitch of a carrier tape is the distance from one depression (e.g. lead edge) to the next (lead edge) along the length of the tape. Carrier tapes are generally wound on reels and transported to the automated assembly location. It is obvious that the part manufacturer and user will desire to use the smallest pitch tape permissible for the size of the electronic component in order to reduce the length of the tape required, and thereby reducing the size and/or number of reels for the required task.
Heretofore, a number of patents and publications have disclosed aspects of a cover tape feeding system, the relevant portions of which may be briefly summarized as follows:
Foreign Patent Publications EP0859541A2, EP0859542A2, EP0859543A2, EP0859544A2, by M. Gfeller et al. (Zevatech Trading AG) filed Feb. 12, 1998 and claiming a priority date of Feb. 18, 1997, the teachings of which are hereby incorporated by reference.
In accordance with the present invention, there is provided an apparatus for supplying components, via a carrier tape having a cover tape thereon and a plurality of pockets retaining components therein, for retrieval by an automated insertion machine, comprising: a carrier tape reel support; a tape feed path and associated tape drive for sequentially positioning the carrier tape so that the components therein may be retrieved at a pick location; a peel edge, about which to peel the cover tape from the carrier tape prior to the component being presented for retrieval at the pick location; and a cover tape path for controlling the travel of the cover tape in a rearward and downward direction so that the cover tape may be disposed of beneath the tape feed path.
In accordance with another aspect of the present invention, there is provided a method of supplying components with a tape feeder, via a carrier tape having a cover tape thereon and a plurality of pockets retaining components therein, for retrieval by an automated insertion machine, comprising the steps of: supplying a spliceable source of the carrier tape; sequentially advancing the carrier tape, with a tape drive, so that the components therein may be retrieved at a pick location; removing the cover tape from the carrier tape at a peel edge prior to the component being advanced to the pick location; and controlling the travel of the cover tape in a rearward and downward direction using a V-bar assembly to alter the direction and a friction tape drive, wherein the cover tape first passes through the V-bar assembly to alter its direction of travel so as to be disposed of beneath the tape feeder.
In accordance with yet another aspect of the present invention, there is provided an apparatus for supplying components, via a carrier tape having a cover tape thereon and a plurality of pockets retaining components therein, for retrieval by an automated insertion machine, comprising a peel edge, about which to peel the cover tape from the carrier tape prior to the component being presented for retrieval at the pick location; and a cover tape drive including a lid having a knurled idler roller associated therewith, a motor, and a rotating drive shaft, coupled to said motor and positioned so that the end thereof extends to the center of the idler roller when the lid is closed, and where said drive shaft includes an O-ring mounted on the end thereof so that said O-ring contacts a surface of the cover tape and imparts a frictional drive force to the cover tape to move it through the cover tape drive.
In accordance with a further aspect of the present invention, there is provided an apparatus for guiding a cover tape, comprising: a rod oriented in a generally horizontal plane and angled with respect to a path of the cover tape; and a roller operatively associated with said rod, where said rod and roller are maintained in a pre-determined relationship as they pivot about a generally vertical axis to facilitate the threading of cover tape therethrough.
One aspect of the invention is based on the discovery that prior-art cover tape paths and drive mechanisms are prone to problems during operation, including varying cover tape travel paths and cover tape drive elements that quickly become covered with adhesive transferred from the cover tape. This discovery avoids problems that arise from the handling of the cover tape once it is removed from the surface of the carrier tape.
This aspect is further based on the discovery of techniques that afford easy service or cleaning of the cover tape path and drive mechanism so as to avoid the need for costly repair or replacement of parts along the cover tape path. This aspect of the invention can be implemented, for example, by a pivotable V-bar assembly that facilitates threading of the cover tape and a cover tape drive having an O-ring drive roller driving the cover tape along a central region between the adhesive-covered edges and causing the cover tape to crown slightly to increase its beam strength. The increased beam strength in turn results in the tape continuing to travel in the direction in which it is driven.
The techniques described herein are advantageous because they are both simple to implement and are highly reliable compared to other approaches. The improved drive path further improves the ease of threading the cover tape in the present system. In addition, it can be used in non-splicing feeders to facilitate improved cover tape handling and disposal to a cover tape receptacle beneath the feeder. The techniques of the invention are advantageous because they provide a range of alternatives, each of which is useful in appropriate situations and permit efficient handling of cover tape, particularly for spliceable feeders where the cover tape stream become essentially endless. As a result of the invention, cover tape handling is improved so as to further enable the consideration and development of fully spliceable component tape feeding systems.